This study will describe the normal and deranged structure of the primate vitreous body using cynomolgus monkeys (Macaca fascicularis). Transmission and scanning electron microscopy using routine and histochemical methods and light-microscopic autoradiography will be employed. Fixation with glutaraldehyde and cetylpyridinium chloride allows hyaluronic acid to be retained in the vitreous body for ultrastructural analysis. Alcian Blue block-staining aids in localizing hyaluronic acid, glycoproteins and sulfated proteoglycans and specific enzyme digestion methods differentiate these three classes of complex carbohydrates. Tritiated fucose and tritiated glucosamine injected into the vitreous allow aspects of the metabolism of vitreous-body glycoproteins to be studied in specific vitreal regions and structures by autoradiography. The injection of tracers, blood cells or iron compounds into the vitreous body will provide various levels of analysis of the reaction of the vitreous to foreign substances. Blood or iron combined with prolapse of the vitreous from its normal comparment in the eye should lead to "condensation" of the vitreous as seen in lesions of the eye clinically. Based on data from normal cynomolgus eyes, the ultrastructure of the collagenous and complex-carbohydrate components in "condensation" of the vitreous will be analyzed. Any direct relationships of these changes in vitreous lesions to later retinal detachments known to occur under similar conditions in experimental animals and in man will be sought in this study.